International rights groups have urged authorities in Iran to release "immediately and unconditionally", one of the country's most prominent human rights lawyers, Nasrin Sotoudeh, who was arrested on Wednesday and taken to the notorious Evin prison.

Sotoudeh's husband, Reza Khandan, said she was told she would be serving a five-year sentence after being convicted in absentia, but added that they have "no idea" what the sentence was related to.

Khandan said their 18-year-old daughter was at home at the time of the arrest.

"My daughter is preparing for university entrance exams that will be held in two weeks," he said. "I don't know how she will manage it in such conditions."

There was no immediate comment from authorities on the arrest.

Sotoudeh, 55, recently represented several women arrested for protesting against the mandatory wearing of headscarves.

In February, Tehran police said that 29 women had been detained for posing in public without their headscarves in the previous weeks.

In a statement sent following the arrest, the Human Rights Watch (HRW) said Sotoudeh "is a human rights champion who should be applauded, not jailed".

"Iran's judiciary again has revealed to its citizens and the international community its disdain for and fear of people who seek to protect human rights," Sarah Leah Whitson, HRW Middle East director said.

In November 2017, Sotoudeh told the Center for Human Rights in Iran (CHRI) that the Revolutionary Court in Evin prison had summoned her, but that she refused to participate in the proceeding, saying she did not believe the court would follow legal procedures, and felt that she would be tried unfairly.

'Outrage'

Commenting on Sotoudeh's detention, Amnesty International called it "an outrage".

Philip Luther, Amnesty's research director for the Middle East and North Africa, said the arrest "is the latest example of the Iranian authorities' vindictive attempts to stop her from carrying out her important work as a lawyer."

Sotoudeh won the European Parliament's prestigious Sakharov rights award in 2012 for her work on high-profile rights and political cases, including juveniles facing the death penalty in the Islamic republic.

She has defended journalists and activists including Nobel Peace laureate Shirin Ebadi and several dissidents arrested during mass protests in 2009.

The human rights lawyer had recently spoken out against a new criminal code that only allowed a small number of lawyers - just 20 in Tehran - to represent individuals charged with national security crimes.

Security forces previously arrested Sotoudeh in 2010. She was later sentenced to 11 years in prison and banned from practicing law for 20 years.

During her time in jail, Sotoudeh staged two hunger strikes in protest at the conditions in Evin and over a ban on seeing her son and daughter.

She was released in September 2013 shortly before Iran's then newly-elected President Hassan Rouhani, who had campaigned on a pledge to improve civil rights, attended the UN General Assembly.

In August 2014, the Lawyers' Court at the Tehran Bar Association overturned the ban on her legal practice.

The Center for Human Rights in Iran (CHRI) also demanded for Sotoudeh's immediate release.

"The arrest of this distinguished attorney, who has dedicated her life to defending detainees held on politically motivated charges, reveals the state's fear of those who defend due process and the rule of law in Iran," Hadi Ghaemi, executive director of CHRI said.